2001 passport overheats

I have replaced the water pump, fan clutch, thermostat, radiator and cap. All to no avail.

Its very random, sometimes it will idle fine for 30 minutes and not got hot. Then you drive it down the road and 20 minutes later it will start to heat up. I am convinced its a BHG but have yet to confirm 100% via a coolant test but I am about to check that out. I have been reading a ton of posts but most refer to the older engines and the coolant leaking by the plugs and causing mis-fire. I an handle replacing the head gaskets but wonder if these engines are common to have cracked blocks when it gets hot ? It hasnt ever went over the top and gotten so hat it wouldnt run, I have always shut it down before it hit that point so its gotten hot but not SUPER hot.

HELP!

2 very important things - the replacement thermostat & radiator cap, are they specifically OEM Isuzu replacements??

The non-OEM thermostats do not work well in these trucks, don't keep them cool enough.

I'm guessing you have the 3.2L V6, how many miles?

What radiator replacement did you choose?

skeen... wow, you are well down the road on this, but...no mention of coolant usage. are you having to add a bunch?

and it seems like you can idle these engines just about forever and not get the upper radiator hose hot. have you felt the upper radiator hose? does it get hot, or stay almost cool? what's the difference at the upper hose when you run it and it the temp gauge reads hot?

not so much blocks cracking, but heads if you run it hot, and of course, warping of mating surface.

//bc

If it did get hot think about swapping out the tranny fluid too as it will be cooked too if the water gets hot....

its the 3.2 v6, 100k miles.

The radiator I got at autozone, not sure on the brand. But the old one looked new and actually had been replaced a short time ago from a wreck. So I dont think it was the issue but it was under warranty so I did it anyway.

The thermostat was a stant, the cap the same.

I did drain the trans fluid as it looked and smelt pretty bad.

It does seem like the thermostat is sticking closed as the upper will be hot and the lower will be much cooler.

Thing is I know that when you have air in the system the thermostat wont function properly. I have burped the system numerous times during this process to get all the air out, but then when it does get hot it overflows and I have to add fluid. It really doesnt drive long enough before it has an overheating spell to determine if its using coolant. Odd thing is the oil is clean as a whistle, no smell out the exhaust or anything.

...The thermostat was a stant, the cap the same.

....

that's probably the problem as someone mentioned before use the dealer oem part. imo. go to local dealer or do it through the mail/phone from stcharles isuzu no minimum free shipping 'internet' discount ask for it, ask for Merlin
http://isuzu.stcharlesauto.com/Department-Parts.aspx

i'll bet that will solve your problems. if you think it is air try putting on incline or jack front up so radiator top is highest point and run and rev for a while after it heats up.

didn't see -- are you using coolant?

//bc

and just saw this. yes that's a sure sign of sticking or incorrect or incorrectly installed thermostat. ...It does seem like the thermostat is sticking closed as the upper will be hot and the lower will be much cooler.....

change that thing pronto. good it's minor.

//bc

One thing I've learned through the years, there are some parts you ALWAYS want to replace with OEM's - specially Isuzu.

Air in the system could be one issue, but get those Stant parts off that truck asap! Then, may want to do a partial drain/refill on your tranny again - keep replenishing that fluid, as it will get hot too, if the engine does.